Methods such as a coloring method, a dye dispersion method, a printing method, and a transfer method are available for forming a color filter used for a color liquid crystal display. In any method, the position accuracy of the respective coloring patterns (for example, red, green, blue and black) is very important. Particularly in a light shielding pattern, a so-called black matrix, the position thereof has to be settled without having spaces between the other coloring patterns. Because of that reason, at present the black matrix is formed so that it overlaps with the other coloring patterns to some extent. The black matrix is formed with a Cr vapor deposition layer in some cases, but because of the high cost thereof, it is considered at present to use a light-sensitive resin containing a dye such as carbon black as described in JP-A-63-314501 (the term "JP-A" as used herewith means an unexamined published Japanese patent application) and JP-A-64-35417.
However, this method involves the disadvantage that the formation of a color filter with this method creates micron-sized projections at the portion at which the black matrix and a color picture element overlap, and these projections result in causing an opposition short (short circuit between the opposite electrode substrates) when a liquid crystal panel is prepared therewith.
In order to improve the above matter, there is considered the method in which a light shielding material layer is formed overall on the R, G and B picture elements, and then a selective etching is carried out in a vertical direction to thereby form a light shielding material layer only at the spaces between the R, G and B picture elements, as disclosed in JP-A-2-287404.
In this method, however, etching has a selectivity in a vertical direction, and therefore it necessary to provide a leveling layer such as a photoresist after providing the light shielding layer in order to compensate for the difference in the level in the light shielding layer, which is originated from the differences in R, G and B, and there is involved therein a disadvantage that the number of steps is increased, and it is very difficult to control the etching amount, which results in a liability to generate a pin hole.
JP-A-1-293306 describes a method in which after coating a dye dispersing light-sensitive resin, patternwise exposing and developing, a black resist is coated and an exposure is made from the non-coated side, followed by developing. However, it is not in any way indicated to remove an overlapped portion by side etching as in the present invention. Further, a black matrix having a large light shielding performance with a sufficient accuracy cannot be formed with the method by back exposing described in this specification, since the exposure of a black color light-sensitive resin from the back does not promote curing to a sufficient depth.
JP-A-64-78221 describes a method in which after coating a colored light-sensitive resin on a substrate, patternwise exposing and developing, an exposure is made from the substrate side. Further, JP-A-2-77702 describes a method in which a patternwise exposure is made from both sides of a colored resist coated side and a non-coated side on a transparent substrate. Further, JP-A-2-53003 describes a method in which after coating a dye dispersing light-sensitive resin, patternwise exposing and developing, an overall exposure is made once again without applying a mask.
The application of this method improves the pattern formability, but an overlapping with the R, G and B picture elements can not be removed, and the flatness is insufficient.